This invention relates generally to forming discrete bundles of documents from a continuous stream of documents. It relates more particularly to a method and apparatus for forming stacks of documents of a predetermined number from a stream of documents.
Modern paper processing lines provide printing on large numbers of documents on a high speed printer in short times. Whether printed from a paper web and subsequently cut into individual pages, or printed on precut sheets, the individual pages are outputted in a continuous stream along a conveyor system. These pages are cut, both transversely and longitudinally in modern high speed sheet cutting units, providing side-by-side streams of paper sheets or pages that must be merged and sorted into books, reports, multi-page invoices, and the like. For brevity, any such discrete group of documents is herein referred to as a report. A problem arises in sorting these pages into discrete ready-to-ship reports, and keeping each report separate from every other report.
The prior art has typically resolved this problem by staggering the stream of documents between reports. Specifically, each page of a report in the prior art is made to overlap another page of the same report, and each report is separated by a gap in the document stream. See U.S. Pat. No. 5,704,604 and DE-A-1 436 485 for some examples of this technique. But simultaneously overlapping individual pages while imposing gaps between other pages, without curtailing printer speed and efficiency, necessarily imposes other problems that must be overcome by ever more complicated arrangements. For example, U.S. Pat. No. 5,704,604 includes rollers to force the individual pages of a report to overlap each other, but which also restrict forward movement of the first few pages of a report to create a gap between reports. These opposing manipulations of the document stream must occur without slowing the overall document stream.
From the broadest perspective then, the prior art takes an endless stream of documents in succession, compresses a portion of the stream by overlapping pages, and subsequently expands another portion of the stream to create a gap between reports. While this method may be effective, it is unnecessarily complicated and imposes certain deficiencies. A single torn or mis-aligned page in the prior art will interrupt the flow and separation of numerous reports, rather than limit the discrepancy to a single report. Multiple unconnected mechanical systems must work in synchronous high speed. The machinery takes up space that is at a premium in commercial print shops. And since most print jobs are multiple printings of reports having the same number of pages, such as books, reports, mass mailings, and the like, the additional capabilities of prior art devices to handle reports of varying page numbers is unused throughout most of the industry.
What is needed in the art is a cost effective and space saving apparatus that separates multi-page reports of a predetermined page number, and a method to do the same. It is an object of the present invention to provide such an apparatus and method, one that overcomes some of the above listed deficiencies in the prior art. As with any invention, simpler solutions tend to be less expensive, more reliable, and more adaptable to varied applications, so it is a further object of this invention to provide an apparatus and method that are simpler than the prior art.
In accordance with the present invention, a machine is provided to separate a continuous stream of pages into discrete reports. This machine comprises a conveyor means to provide a continuous stream of pages seriatim in a first direction, means to determine which page in the continuous stream is a last page of a report, means for moving each page of a report from the continuous stream onto a first location of a holding area, and means for shifting each page immediately following a last page of a report, until and including the last page of the next subsequent report, onto a second location of the holding area, said second location being shifted either laterally or longitudinally from said first location. The conventions xe2x80x98last pagexe2x80x99 and xe2x80x98reportxe2x80x99 used herein are explicitly specified in other sections of this disclosure.
The present invention also includes the method for separating one or more endless stream of pages into one or more corresponding stacks of reports. This method comprises the steps of moving each page of a report from the endless stream into a first position on a holding area, determining which page in the endless stream of pages is a last page of a report, and moving each page immediately following said last page of a report, until and including the last page of the next subsequent report, to a second position on a holding area, said second position being staggered from said first position.
The present invention thereby takes an endless stream of individual pages and divides them into discrete reports, said reports formed into a staggered stack such that each discrete report only partially overlaps adjacent reports.
The present invention includes forming a single staggered stack of reports from a single endless stream of pages, and multiple staggered stacks of reports from multiple endless streams of documents, each staggered stack of reports corresponding to one endless stream of pages.
The preferred embodiment employs an overhead conveyor system to move each page from the endless stream into one of the two positions that make up the staggered stack of reports. This embodiment uses a fixed driven shaft located nearest the endless stream of documents and two opposing idling shafts, each connected to the driven shaft by rubber conveyor belts or bands.
A variable speed motor powers the driven shaft so that the shaft""s speed moves each page faster than the incoming stream of documents, thus xe2x80x98pullingxe2x80x99 each individual page from the stream. A single speed motor driving the shaft faster than the incoming stream of pages is sufficient for simple applications where the variety of print jobs does not greatly vary. Where the upstream printing and cutting devices are capable of delivering streams of documents over a very wide variety of speeds into the present invention, such as in highly flexible commercial printing operations, a variable speed motor that can more closely match the speed of the incoming document stream may alternatively be provided.
The belts connecting one idling shaft direct pages toward a first position on the staggered stack of reports and the belts connecting the other idling shaft direct pages toward a second position. The idling shafts are alternately raised or lowered so that only one set of belts contacts the incoming page, directing it to one or the other position. These idling shafts may either be horizontal, or may be canted downward and away from the centerline of the staggered stack. When horizontal, the conveyor belts or bands angle away from the longitudinal centerline of the staggered stack so as to direct each page to one side or the other of the stack of reports. When canted, the conveyor belts may be parallel to the longitudinal centerline, and the cant of the successive belts drives each page to one side or the other of the staggered stack of reports.
An alternative embodiment comprises a single idling shaft that is laterally shiftable, or two idling shafts operating in unison, thus directing each incoming page toward the first or second position on the holding area. Multiple such overhead conveyor systems may be employed in side-by-side relation to each other in order to handle multiple endless streams of documents.
Another alternative embodiment staggers the stacks of reports longitudinally rather than laterally, to better enable the handling of more than two endless streams of documents considering space restraints imposed by lateral staggering of stacks of reports. This embodiment also employs overhead conveyor systems, but wherein the speed of the conveyor system varies to move any individual page to either of the longitudinally staggered positions. The idling shaft of this embodiment is not laterally shiftable as above.
Further details regarding specific embodiments are expounded in the following sections.